This invention relates to a tape cassette suitable for use for a magnetic recording/reproducing apparatus such as, for example, a video tape recorder (VTR) or the like, and more particularly, to a tape cassette which has a tape-like record medium received in a casing while being wound on tape reels and is provided therein with a reel brake mechanism for regulating rotation of the tape reels in no-use thereof, such as an 8 mm video tape cassette, a digital video cassette or the like.
It has been conventionally known in the art that a tape cassette which has a tape-like medium received in a casing while being wound on a pair of tape reels is provided with a reel brake mechanism for keeping each of the tape reels from being rotated in non-use of the tape cassette. The reel brake mechanism is generally constructed in such a manner that an elastic member such as a torsion coil spring, a leaf spring or the like is arranged in the casing so as to urge a brake member against a tooth-like ruggedness provided on an outer periphery of a flange of each of the tape reels. When the tape cassette is charged in a recording/reproducing apparatus, a reel brake release member of the recording/reproducing apparatus is abutted against the reel brake member to rearwardly slide the reel brake member against elastic force of the elastic member or spring, to thereby release the reel brake member from the tape reels, so that the tape reels may rotate. For such a reel brake mechanism, various structures for stably operating the reel brake member have been proposed.
For example, Japanese Utility Model Application Laid-Open Publication No. 161578/1984 discloses a structure for arranging a high reel brake to guide the reel brake on an inner surface of a casing and providing L-shaped ribs in a lower casing member to slidably guide the reel brake in the ribs. Also, Japanese Utility Model Application Laid-Open Publication No. 24575/1989 discloses a structure wherein a guide rib is arranged in an upper casing member to slide a reel brake member on the guide rib or a guide member is provided separately from a casing to slide the reel brake member on the guide member.
Unfortunately, the former structure described above causes positioning of the reel brake member to be unstable during assembling of the tape cassette, resulting in incorporation of the reel brake member in the casing being highly troublesome, because the height of the reel brake member is large as described above. The latter structure described above is simplified in construction but causes sink marks to be markedly produced on an outer surface of the tape cassette during molding of the casing to deteriorate an appearance of the cassette because the rib is arranged in the upper casing member. More particularly, although arrangement of the guide rib for guiding slide of the reel brake member in the upper casing member renders movement of the reel brake member stable, it causes sink marks to be produced on a portion of the upper casing member on which the guide rib is arranged during the molding, to thereby deteriorate an appearance of the tape cassette, resulting in a commercial value of the tape cassette being highly deteriorated, because the portion is substantially remote from gate positions of the tape cassette. Also, in the latter structure, arrangement of the separate guide member in the lower casing member causes the number of parts to be increased, leading to a failure to facilitate assembling of the tape cassette.